Analytical modeling of the heat-affected zone in laser-assisted milling of AerMet100 steel

Compared with conventional milling, laser-assisted milling (LAM) enhances the productivity of difficult-to-cut materials and is a green process due to the elimination of coolant. However, this heat-assisted process may induce a detrimental heat-affected zone (HAZ, generally referred to as phase transformation zone) in the workpiece. This paper presents an analytical model to predict the HAZ produced by laser heating in LAM of AerMet100 steel, in which the size of HAZ is determined by comparing the steady temperature field with the phase transformation temperature of workpiece material. A series of laser heating and LAM experiments are performed to validate the HAZ model. XRD technique is employed to analyze the microstructures in the heated and machined surface layers. Phase compositions and retained austenite content of each specimen are compared with those of the base material. The results indicate that the proposed model is feasible. In addition, the effects of different laser parameters on the HAZ are discussed. The size of the HAZ increases significantly with increasing laser power and decreases significantly with increasing feed speed. The HAZ width increases with the increase of laser spot size, and it appears the opposite change for the HAZ depth. This work can be applied to determine the process parameters in LAM that will yield no residual HAZ in the workpiece after machining.